Propeller



Feb. 23, 1932.

J. R. cRoNlsTER PROPELLER l med March 12. 195o 2 Sheets-Siheet 2Patented Feb. 23, 1932 UNITD STATES PATENT FCE JACKSON R. CRONISTER, OFJEANNETTE, PENNSYLVANIA PROPELLER This invention relates to propellers.

One important object of the invention is to provide an improved generalconstruction of propellers.

A second important object of the invention is to provide a propellerhaving improved thrust.

A third important object of the invention is to provide a novelpropeller having great strength and compact-ness.

A fourth important object of the invention is to provide an improvedform of propeller having proper balance at all speeds.

A fifth important object of the invention is to provide an improved formof propeller having a novel hub arrangement.

With the above and other objects in view, the invention consists ingeneral of certain novel details of construction and combinations ofparts hereinafter more fully described, illustrated in the accompanyingdrawings and claimed.

In the accompanying drawings, like characters of reference indicatecorresponding parts in the several views, and:

Figure 1 is a rear view of the invention;

Figure 2 is a side view thereof;

Figure 3 is a section on the line 3f-3 of Figure 1; I

Figure 4 is a rear elevation of a modified form of the invention;

Figure 5 is a section on the line 5 5 of Figure 6; and

Figure 6 is a section on the line 6 6 of Figure 4.

Thepropeller forming this invention is a two bladed propeller, eachblade of which has a leading edge 10 slightly convex in front elevationin the direction of attack and a trailing` edge 11 slightly concave insaid direction of attack, the propeller being designed to rotate in thedirection of the arrow A in Figure 1. Both leading edges lie in a planeatV right angles to the axis of rotation of the pro-peller and thetrailing edges lie in a second plane spaced rearwardly of the leadingedge plane. Each trailing edge substantially at right angles to therespective leading edge so that the two planes above mentioned arespaced a distance equal approximately JC0 one-fourth the pitch of themSimilarly, the form shown in Figures 4, 5

and 6 is provided with a hub 15 of conical form, this being thepreferred form of the invention, and the helical blade surfaces mergeinto this hub by proper curves so as to prevent the setting up of eddycurrents causing loss of propulsive power. Moreover, this con icalforno, by forcing the air outwardly as the propeller is rotated, causesincreased air density at the rear inner parts of the propeller andprevents cavitation and losses caused thereby. The merging of thehelical and conical surfaces is effected by curved connecting surfacestangent to the conical and helical surfaces as can best be seen inFigure 5.

There has thus been provided a simple and eiiicient device of the kinddescribed and for the purpose specified.

It is obvious that changes may be made in the form and construction ofthe invention without departing from the principles thereof. It is not,therefore, desired to confine the invention to the exact form hereinshown and described but it is desired to include all such as come withinthe scope claimed.

Having thus described the invention, what is claimed is 1. A propellerhaving a hub and a. pair of oppositely disposed blades having leadingand trailing edges, the trailing edges of said blades being positionedin a plane at right angles to the axis of rotation of the propeller, andthe leading edges of the blades being positioned in a second plane atright angles to said axis and spaced along said axis rear- "ri wardly ofthe first plane, each leading edge being spaced substantially ninetydegrees about the axis of the propeller from the corresponding trailingedges and the planes in which the leading and trailing edges lie beinglilo spaced approximately one-fourth of the pitch distance of thepropeller.

2. A propeller having a hub and a pair of oppositely disposed bladeshaving leading and trailing edges, the trailing edges of said bladesbeing positioned in a plane at right angles to the axis of rotation ofthe propeller, and the leading edges of the blades being positioned in asecond plane at right angles to said axis and spaced along said axisrearwardly of the first plane, said leading edges being convex in thedirection of attack and the trailing edges being concave in saiddirection, each leading edge being spaced substantially ninety degreesabout the axis of the propeller from the corresponding trailing edgesand the planes in which the leading and trailing edges lie being spacedonefourth of the pitch distance of the propeller.

3. A propeller having a hub and a pair of oppositely disposed bladeshaving leading and trailing edges, the trailing edges of said bladesbeing` positioned in a plane at right angles to the axis of rotation ofthe propeller, and the leading edges of the blades being positioned in asecond plane at right angles to said axis and spaced along said axisrearwardly of the first plane, each leading edge being connected to thecorresponding trailing edge by helical surfaces terminating outwardly ina concave edge, each leading edge being spaced substantially ninetydegrees about the axis of the propeller from the corresponding trailingedges and the planes in which the leading and trailing edges lie being'spaced approximately one-fourth of the pitch distance of the propeller.

4. A propeller having a hub and a pair of oppositely disposed bladeshaving leading and trailing` edges, the trailing edges of said bladesbeing positioned in a plane at right angles to the axis of rot-ation ofthe propeller, and the leading edges of the blades being positioned in asecond plane at right angles to said axis and spaced along said axisrearwardly of the first plane, said leading edges being convex in thedirection of attaclnand the trailing edges being concave in saiddirection, each leading edge being connected to the correspondingtrailing edge by helical surfaces terminating outwardly in a concaveenge, each leading edge being spaced substantially ninety degrees aboutthe axis of the propeller from the corresponding trailing edges and theplanes in which the leading and trailing coges lie being spacedapproximately one-fourth of the pitch distance of the propeller.

5. A propeller having a hub and a pair of oppositely disposed bladeshaving leading and trailing edges. the trailing edges of said bladesbeing positioned in. a plane at right angles to the axis of rotation ofvthe propeller and the leading edges of the bla es being positioned in asecond plane at rignt angles to said axis and spaced along said axisrearwardly of the first plane, said hub being of conical form with itsapex forward and having the helical surfaces merging into the surface ofthe cone along curved surfaces tangent to the conical and helicalsurfaces.

6. A propeller having a` hub and a pair of oppositely disposed bladeshaving leading and trailing edges, the trailing edges of said bladesbeing positioned in a plane at right angles to the axis of rotation ofthe propeller, and the leading edges of the blades being positioned in asecond plane at right angles to said axis and spaced along said axisrearwardly of the first plane, said leading edges being convex in thedirection of' attack and the trailing edges being concave in saiddirection, said hub being of conical form with its apex forward andhaving the helical surfaces merging into the surface of the cone alongcurved surfaces tangent to the conical and helical surfaces.

7. A propeller having a hub and a pair of oppositely disposed bladeshaving leading and trailing edges, the trailing edges of said bladesbeing positioned in a plane at right angles to the axis of rotation ofthe propeller7 and the leading edges of the blades being positioned in asecond plane at right angles to said axis and spaced along said axisrearwardly of the iirst plane, each leading edge being connected to thecorresponding trailing edge by helical surfaces terminating outwardly ina concave edge, said hub being of conical form with its apex forward andhaving the helical surfaces merging into the surface of the cone alongcurved surfaces tangent to the conical and helical surfaces.

8. A propeller having a hub and a pair of o-ppositely disposed bladeshaving leading and trailing edges, the trailing edges of said bladesbeing positioned in a plane at right angles to the axis of rotation ofthe propeller, and the leading edges of the blades being positioned in asecond plane at right angles to said axis and spaced along said axisrearwardly of the first plane, said leading edges being convex in thedirection of attack, and the trailing edges being concave in saiddirection, each leading edge being connected to the correspondingtrailing edge by helical surfaces terminating outwardly in a concaveedge, said hub being of conical form with its apex forward and havingthe helical surfaces merging into the surface of the cone along curvedsurfaces tangent to the conical and helical surfaces.

9. A propeller having a hub and a pair of o-ppositely disposed bladeshaving leading and trailing edges, the trailing edges of said bladesbeing positioned in a plane at right angles to the axis of rotationofthe propeller.` and the leading edges of the blades being positionedin a second plane at right angles to said axis and spaced along saidaxis rearwardly of the first plane, each leading edge being spacedsubstantially ninety degrees about the axis of the propeller from thecorresponding trailing edges and the planes in which the leading andtrailing edges lie being spaced approximately one-fourth of the pitchdistance of the propeller, said hub being of conical form with its apexforward and hav-A ing the helical surfaces merging into the surface ofthe cone along curved surfaces tangent to the conical and helicalsurfaces.

l0. A propeller having a hub and a pair of oppositely disposed bladeshaving leading and trailing edges, the trailing edges of said bladesbeing positioned in a plane at right angles to the axis of rotation ofthe propeller, and the leading edges of the blades being positioned in asecond plane at right angles to said axis and spaced along said axisrearwardly of the first plane, said leading edges being convex in thedirection of attack and the trailing edges being concave in saiddirection, each leading edge being spaced substantially ninety degreesabout the axis of the propeller from the corresponding trailing edgesand the planes in which the leadand trailing` edges lie being spacedonefourth of the pitch distance of the propeller, said hub being ofconical form with its apex forward and having' the helical surfacesmerging into the surface of the cone along curved surfaces tangent tothe conical and helical surfaces.

ll. A propeller having a hub and a pair of oppositely disposed bladeshaving leading and trailing edges, the trailing edges of said bladesbeing positioned in a plane at right angles to the axis of rotation ofthe propeller, and the leading edges of the blades being positioned in asecond plane at right angles to said axis and spaced along said axisrearwardly of the first plane, each leading edge being connected to thecorresponding trailing edge by helical surfaces terminating outwardly ina concave edge, each leading edge being spaced substantially ninetydegrees about the axis of the propeller from the corresponding trailingedges and the planes in which the leading and trailing edges lie beingspaced approximately one-fourth of the pitch distance of the propeller,said hub being of conical form with its apex forward and having thehelical surfaces merging into the surface of the cone along curvedsurfaces tangent to the conical and helical surfaces.

12. A propeller having a hub and a pair of oppositely disposed bladeshaving leading and trailing edges, the trailing edges of said bladesbeing positioned in a plane at right angles to the axis of rotation ofthe propeller, and the leading edges of the blades being positioned in asecond plane at right angles to said axis and spaced along said axisrearwardly of the first plane, said leading edges being convex in thedirection of attack, and

the trailing edges being concave in said direction, each leading edgebeing connected to the corresponding trailing edge by helical surfacesterminating outwardly in a concave edge, each leading edge being spacedsubstantially ninety degrees about the axis of the propeller from thecorresponding trailing edges and the planes in which the leading andtrailing edges lie being spaced approximately one-fourth of the pitchdistance of the propeller, said hub being of conical form with its apexforward and having the helical surfaces merging into the surface of thecone along curved surfaces tangent to the conical and helical surfaces.

In testimony whereof l aflix my signature` JACKSON R. CROhlfS'IER`

